Method of charging cellulose digesters and means therefor



P. A. FRESK 4 4 6 2 0 0 R m l E R Fu H T s N E M D N A S R E T s .E G I D E S O L U L L E C G N I G R A H C .F O D O H T E M April 28, 1931.

Filed Sept. 25, 1928 NIB ww on NR w uvn s I l l wl I v Y a a Q a l .1 -53 V WW HM ATTORNEYS.

Patented Apr. 28, 1931 UNirE'o STATES PATENT oF 'm .PER ALBERT FRESK, OF ROBERTSFORS, SWEDEN METHOD OF CHARGING GELLULOSE DIGESTERS AND MEANS THEREFOR Application filed. September 25, 1928, Serial No. 308,33Q, and. in Sweden September 1, 1928.

It is previously known to charge cellulose digesters by. introducing the charge into the digester under the influence of a flowing medium, preferably an air-stream, whereby the charge will be evenly and tightly packed.

For carrying this method into effect, an injector-like contrivance is used which is so devised that the charge Will, at the transition from a pipe or nozzle into a wider pipe opening into the digester, be subjected to the influence of an air-stream brought about by means or" a fan, said air-stream being forced in through an annular opening between the two pipes. The larger pipe extends for a certain length into the digester, the air blown in escaping again between the pipe and the wall of the di-gester. Then the escaping air is again conducted to the fan, through which a vacuum is produced in the digester at the same time.

This known method brings about proper filling, it is true, whereas it will be found im possible in this manner also to fill the uppermost part of the digester with chips. For this reason it has been necessary to interrupt the filling operation as soon as the charging material would reach such a level as to touch the spreading means provided in the apparatus and suspending into the digester. There- I fore, it has not been possible to bring about complete filling in the manner described, inasmuch as a more or less smooth cone would always be formed under the mouth of the pipe conducting the chips into the digester. Moreover, the ventilator would, toward the end of the filling operation, be subjected to the risk of chips being sucked into the same. Thus there would be produced an empty space in the digester amounting about to 8% of the volume of the whole digester, which space cannot be filled with the apparatus. Hitherto, it has been necessary to fill the said empty space manually upon removal of the apparatus from the neck of the digester.' One or two men would then descend into the upper part of the digester to spread the charge falling down from the supply conduit for the chips by means of shovels toward the sides of the digester, until the latter would be completely filled,

"apparatusand without the same having t0 'be disconnected.

" space This subsequent filling by hand requires much time and is also dangerous to the health by reason of the high temperature and onaccount of the presence of sulphur gases in the digester. Moreover, the subsequent filling by hand is far behind fillingjbrought about by blowingthe charge into the digestemas far as tightness is concerned, and the total output will consequently be less.

The object of the present invention is to overcome the said difliculties, and to bring about the same compactness ofthe filling in the upper part ofthe digester as in the other parts thereof, by means of one and the same The novel method according .to the invention consists in that thecirculation of the air coming from the fan an'dflowing throughfthe filling device, the digester and the fan, is interrupted toward' the end of the filling operation, so that the air is then blownlout int the atmosphere from the digester. It has been found that the chips will by this means be carried out towardthe walls of the digester Y to a greater extentthan before, so that the surface of the char-ge will finally 'formfa conical recess having its apex directeddownwards. In this manner the filling is rend'ered very complete, and upon finishing the saine there is only left the space occupied by the pipe through which the chips are .blOWn into the ,digester. This. empty spaceican, if desired, be readily filled subsequently by i simply admitting a corresponding quantity of chips. In order to collect the chips forced out ofthe digester by the streamv of air, there is preferablyprovided a basket of metal cloth overthe outlet of the digester, said basket beingadapted to catch the chips discharged,

The accompanying drawing illustrates van embodiment of the invention by way of example, the filling device being viewed in 10ngitudinal section. i

' The air-strea1n required for the charging is conducted from a fan or othersuitable air compressor through the conduit liinto, the Y 2. This fan'may be slimilartotheztan ,in my Patent No. 1,6 6,69 The charge (t e ke ipeli wh sk is fil ed into heeeper 31 the annular dampers 25 and 26 which are turned by the two handles 23 and 24 to such an extent as to open the dampers outwardly. At the same time the damper 29 is introduced into an opening 27 in the conduit 22 between the two dampers 25 and 26. By this means the sucking of air from the digester is interrupted, and the air is instead forced out through the slots 34 of the annular damper 25, while the fan is now sucking air from the outside through. the slots 35 of the damper 26. In order to facilitate collection of any chips that may be forced out with the airstream through the slots of the damper 25, the latter is surrounded by a catching device such as a round basket 30 ofmetal cloth.

What I claim is i 1. Method of charging a cellulose digester by first introducing the charge into the digester under the influence of the circulation of compressed fluid, then conducting the .fluidout of the digester, thereupon interrupting the circulation of the fluid towards the end of the filling operation in such a manner that the charge at the top of the digester is stacked in the formof an inverted cone,

while the'fluid from the digester is blown out into the atmosphere.

2. Apparatus for charging a digester, comprising a hopper communicating with the filling opening of the digester, a. drum surrounding the mouth of the hopper, anozzle on said drum extending into the digester opening, a conduit from a source of c0mpressed fluid adapted to conduct the fluid into said drum, past the hopper mouth through said nozzle into the digester, a sec ond conduit for returning the fluid to said source from said opening, and means in said second conduit for directing the fluid flow into the atmosphere.

13. An apparatus as described in claim 2, said fluid changing means comprising a damper to be inserted transversely in said conduit and sleeves revolubly mounted on each side of said damper and provided with apertures adapted to register with corre sponding apertures in the conduit when the sleeves stand in open position and to close said apertures when the sleeves stand in closed position.

each side of said damper and provided with apertures adapted to register with corresponding apertures in the conduit when the sleeves stand in open position and to close said apertures when the sleeves stand in closed position, and a perforated basket enclosing one of said sleeves.

In testimony whereof I affix my signature.

PER ALBERT FRESK.

4. An apparatus as described in claim 2,

said fluid changing means comprising a damper to be inserted transversely in said conduit and sleeves revolubly mounted on 

